Technical Abstract:
A hyperspectral fluorescence imaging system was developed and used to obtain several two-waveband spectral ratios on leafy green vegetables, represented by romaine lettuce and baby spinach in this study. The ratios were analyzed to determine the proper one for detecting bovine fecal contamination on romaine lettuce and baby spinach. Two wavebands corresponding to fluorescence emission peaks for fecal matter and chlorophyll a were considered useful to detect fecal contamination on samples of relatively high chlorophyll content such as leafy green vegetables. The emission peak from bovine fecal matter was around 670 nm and the emission peak from green plant leaves was observed at 685 nm. The results indicated that a two-waveband ratio, 666nm over 680nm, could be applied to the multispectral algorithm for contamination detection. The threshold and erosion analyses were performed to reduce false positive response emanating from leaf vein and inter-veinal regions of leafy green vegetables. The results showed that the fluorescence-based hyperspectral/multispectral imaging system can successfully detect fecal contamination on leafy green vegetables.